JP7077168B2 - Developer regulators, developing equipment, process cartridges and electrophotographic image forming equipment - Google Patents

Description

The present invention relates to a developer regulating member, a developing device, a process cartridge and an electrophotographic image forming apparatus used in an electrophotographic image forming apparatus.

As a developing device used in an electrophotographic image forming device, a developing device having a developing agent carrier and a developing agent regulating member is widely known. The developer regulating member has a role of forming a thin layer of the developer and imparting a frictional charge (tribo) to the developer at the regulating portion in contact with the developer carrier.

Patent Document 1 discloses a developer-regulating member which is a copolymer in which a resin layer is formed on the surface of the developer-regulating member and the resin layer has at least a methyl methacrylate monomer and a nitrogen-containing vinyl monomer as monomer components. ing. Further, Patent Document 1 discloses that the developer regulating member can give a stable charge to the developer on the developer carrier with a high charge amount.

Japanese Unexamined Patent Publication No. 2000-39765

According to the studies by the present inventors, it may not be possible to uniformly triboelectricly charge the developer even if the developer regulating member according to Patent Document 1 is used due to the recent reduction in the particle size of the developer. rice field. Insufficient charge in the developer causes fog in the electrophotographic image.

One aspect of the present invention is to provide a developer regulating member capable of generating a uniform frictional charge even for a developer having a small particle size. Another aspect of the present invention is to provide a developing apparatus capable of forming a high-quality electrophotographic image. Another aspect of the present invention is to provide a process cartridge that contributes to the formation of high quality electrophotographic images. Still another aspect of the present invention is to provide an electrophotographic image forming apparatus capable of forming a high-quality electrophotographic image.

According to one aspect of the invention
It is a developer regulating member that regulates the thickness of the layer of the developer supported on the surface of the developer carrier, and has a regulating portion in contact with the developing agent, and the regulating portion contains a thermoplastic acrylic resin.
The thermoplastic acrylic resin has a DSC curve obtained when the temperature is raised from −100 ° C. to 150 ° C. at a heating rate of 20.0 ° C./min using a differential scanning calorimetry (DSC). Provided is a developer regulating member in which a first endothermic peak having a peak top at + 50 ° C. or higher and a second endothermic peak having a peak top at + 20 ° C. or lower are present in the differential curve of.

According to another aspect of the present invention, the developing apparatus includes a developer carrier and a developer regulating member arranged in contact with the surface of the developer carrier, wherein the developer is provided. A developing device in which the regulating member is the above-mentioned developer regulating member is provided.

According to still another aspect of the present invention, it is a process cartridge that can be attached to and detached from the main body of the electrophotographic image forming apparatus, and is arranged in contact with the developer carrier and the surface of the developer carrier. A process cartridge comprising a developer regulating member and the developer regulating member being the above-mentioned developer regulating member is provided.

According to still another aspect of the present invention, the electrophotographic image forming apparatus includes a developer carrier and a developer regulating member arranged in contact with the surface of the developer carrier. Provided is an electrophotographic image forming apparatus in which the developer regulating member is the above-mentioned developer regulating member.

According to one aspect of the present invention, it is possible to obtain a developer regulating member capable of generating a uniform frictional charge even for a developer having a small particle size. According to another aspect of the present invention, it is possible to obtain a developing device capable of forming a high-quality electrophotographic image. According to another aspect of the present invention, it is possible to obtain a process cartridge that contributes to the formation of a high-quality electrophotographic image. According to still another aspect of the present invention, it is possible to obtain an electrophotographic image forming apparatus capable of forming a high-quality electrophotographic image.

It is a schematic diagram which shows an example of the phase separation structure of a thermoplastic acrylic resin. It is sectional drawing to explain an example of the developer regulation member. It is sectional drawing for demonstrating another example of a developer regulation member. It is sectional drawing for demonstrating another example of a developer regulation member. It is sectional drawing which shows an example of a developing apparatus. It is sectional drawing which shows an example of a process cartridge. It is sectional drawing which shows an example of an electrophotographic image forming apparatus. It is a schematic diagram which shows an example of the manufacturing apparatus of a developer regulation member.

Hereinafter, embodiments for carrying out the present invention will be described, but the present invention is not limited thereto.

[Developer control member]
The developer regulating member is a member that regulates the thickness of the developer layer supported on the surface of the developer carrier. The developer regulating member has a regulating portion in contact with the developer. The regulatory section also includes a thermoplastic acrylic resin. This thermoplastic acrylic resin has a DSC curve obtained when the temperature is raised from -100 ° C to 150 ° C at a heating rate of 20.0 ° C / min using a differential scanning calorimetry (DSC). In the differential curve of, the first heat absorption peak and the second heat absorption peak exist. The first endothermic peak is an endothermic peak having a peak top at + 50 ° C. or higher in this differential curve, and the second endothermic peak is an endothermic peak having a peak top at + 20 ° C. or lower in this differential curve. In the differential curve, the temperature of the endothermic peak corresponds to the glass transition point.

Thermoplastic Acrylic Resin In the differential curve of the thermoplastic acrylic resin, there is at least one first heat absorption peak having a peak top at + 50 ° C. or higher, preferably + 100 ° C. or higher, and a peak at + 20 ° C. or lower, preferably 0 ° C. or lower. There is at least one second heat absorption peak with a top. Typically, in the differential curve, there is only one endothermic peak having a peak top at + 50 ° C. or higher, and only one endothermic peak having a peak top at + 20 ° C. or lower.

Examples of the thermoplastic acrylic resin in which the first heat absorption peak and the second heat absorption peak are present in the differential curve include i) the first polymer showing the first heat absorption peak and the second heat absorption peak. A thermoplastic acrylic resin containing a second polymer, and ii) a block having a first polymer block showing a first heat absorption peak and a second polymer block showing a second heat absorption peak. Examples thereof include thermoplastic acrylic resins which are polymers.

Hereinafter, the polymer or polymer block that causes the first endothermic peak may be referred to as the first component, and the polymer or polymer block that causes the second endothermic peak may be referred to as the second component.

FIG. 1 shows an example of a phase-separated structure made of the thermoplastic acrylic resin. In this example, the first component 201 and the second component 202 form a phase-separated structure. The phase-separated structure is observed using, for example, a transmission electron microscope (TEM). In the case of TEM observation, if a hydrophilic dyeing agent such as phosphotungstic acid is used, it is possible to identify the phase-separated structure by the brightness and darkness of the observed components.

The present inventors uniformly triboelectricly charge the surface of the developer when the first and second heat absorption peaks are present in the differential curve of the thermoplastic acrylic resin contained in the regulatory section, resulting in insufficient charge of the developer. It was found that the charge was suppressed and the fog was less likely to occur. The reason why the insufficient charge of the developer is suppressed is presumed as follows.

During actual use of the developer regulating member, while the developer passes through the developer regulating member, the thermoplastic acrylic resin constituting the surface of the regulated portion of the developer regulating member comes into contact with the developer, and the developer becomes thermoplastic acrylic. Roll on the resin. Due to the rolling of the developer, the surface of the developer is uniformly triboelectrically charged, so that the insufficient charge of the developer is suppressed. The reason why the developer rolls on the thermoplastic acrylic resin is that the first component and the second component of the thermoplastic acrylic resin form a phase-separated structure incompatible with each other. In the differential curve, when the heat absorption peak exists only at + 50 ° C. or higher, the thermoplastic acrylic resin becomes a glass state at a temperature during actual use, for example, at room temperature (25 ° C.), and the hardness of the surface of the regulation portion increases. The developer becomes slippery. Therefore, while the developer passes through the developer regulating member, the developer simply moves while sliding on the surface of the regulated portion, and the developer does not easily roll on the surface of the regulated portion. Therefore, the triboelectric charge on the surface of the developer is reduced. It becomes non-uniform. Further, when the endothermic peak is present only at + 20 ° C. or lower in the differential curve, the tackiness of the surface of the regulated portion containing the thermoplastic acrylic resin is increased, and the developer is likely to adhere to the surface of the regulated portion. Therefore, while the developer passes through the developer regulating member, the developer adheres to the surface of the regulated portion, and the developer is less likely to roll on the surface of the regulated portion. As a result, the triboelectric charge on the surface of the developer becomes non-uniform.

The present inventors have found that when the first and second endothermic peaks are present, the slipperiness and adhesiveness of the developer on the regulated portion of the developer regulating member can be designed within an appropriate range. .. As a result, the developer can be satisfactorily rolled on the regulated portion, and the triboelectric charge on the surface of the developer can be made uniform.

As described above, the thermoplastic acrylic resin can be, for example, a mixture of i) a first polymer exhibiting a first endothermic peak and a second polymer exhibiting a second endothermic peak. In the case of such a thermoplastic resin, the mixture of the first polymer and the second polymer is, for example, a state in which the other polymer is dispersed in one polymer.

Further, the thermoplastic acrylic resin is, for example, a block copolymer having ii) a first polymer block showing a first heat absorption peak and a second polymer block showing a second heat absorption peak. be able to. In the case of such a thermoplastic acrylic resin, for example, the polymer block A derived from the same type of monomer and the polymer block B derived from the same type of monomer different from the monomer of A are used. It can be an AB type block copolymer or an ABA type block copolymer present in one molecule. In this case, one of the polymer blocks A and B is the first polymer block, and the other is the second polymer block.

The thermoplastic acrylic resin is preferably ii). In the block copolymer, each monomer unit constituting the thermoplastic acrylic resin is chemically bonded. Therefore, in the block copolymer, the microphase-separated state designed at the time of polymerization can be maintained more stably even after being processed into the regulated portion of the developer regulating member. Therefore, in the case of a block copolymer, it is easy to maintain a good rolling state of the developer on the regulated portion, and it is easy to maintain the uniformity of triboelectric charging on the surface of the developer.

Whether or not it is a block copolymer can be confirmed by using Kendrick Mass Defect analysis from the mass spectrum (MS) measured by matrix-assisted laser desorption / ionization mass spectrometry (MALDI-TOFMS) or the like.

The first component of the thermoplastic acrylic resin is, for example, a first polymer or a first polymer block synthesized from a methacrylic acid ester or an acrylic acid ester monomer (heat absorption to + 50 ° C. or higher in the differential curve). Those with a peak). The second component is, for example, a second polymer or a second polymer block synthesized from a methacrylic acid ester or an acrylic acid ester monomer (having a heat absorption peak at + 20 ° C. or lower in the differential curve). ).

Examples of the monomer used for the synthesis of the first component include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate and methacrylic acid. Methacrylic acid esters such as isobornyl acid, phenyl methacrylate and 2-hydroxyethyl methacrylate, acrylic such as methyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, phenyl acrylate, 2-hydroxyethyl acrylate and the like. Examples include acid esters.

Among these, methyl methacrylate is preferably used as the monomer used for the synthesis of the first component. That is, the first component is preferably composed of a repeating unit derived from methyl methacrylate.

Examples of the monomer used for the synthesis of the second component include n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate and 2 methacrylate. -Methyl acrylates such as ethylhexyl, pentadecyl methacrylate, dodecyl methacrylate, phenoxyethyl methacrylate, 2-methoxyethyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n- acrylate. Butyl, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, benzyl acrylate, phenoxyethyl acrylate, acrylic Acrylic acid esters such as 2-methoxyethyl acid may be mentioned.

Among these, n-butyl acrylate or 2-ethylhexyl acrylate is preferably used as the monomer used for the synthesis of the second component. That is, the second component preferably consists of repeating units derived from n-butyl acrylate or 2-ethylhexyl acrylate.

When the thermoplastic acrylic resin is a mixture of the first polymer and the second polymer, the weight average molecular weight Mw of the first polymer (first component) is 1 × 10 ⁴ or more and 5 × 10 ⁴ or less. Is preferable. In this case, while the developer passes through the developer regulating member, the rolling of the developer is improved and the surface of the developer is triboelectrically charged, so that the insufficient charge of the developer is suppressed.

When the thermoplastic acrylic resin is a mixture of the first polymer and the second polymer, the weight average molecular weight Mw of the second polymer (second component) is 1 × 10 ⁴ or more and 1 × ¹⁰⁵ or less. Is preferable. In this case, while the developer passes through the developer regulating member, the rolling of the developer is improved and the surface of the developer is triboelectrically charged, so that the insufficient charge of the developer is suppressed.

The weight average molecular weight Mw of the block copolymer is preferably 1 × 10 ⁴ or more and 9 × ¹⁰⁵ or less. In this case, while the developer passes through the developer regulating member, the rolling of the developer is improved and the surface of the developer is triboelectrically charged, so that the insufficient charge of the developer is suppressed.

The content of the first component with respect to the total amount of the thermoplastic acrylic resin is preferably 20% by mass or more and less than 80% by mass. Therefore, it is preferable that the content of the first polymer with respect to the total amount of the thermoplastic acrylic resin or the content of the first polymer block with respect to the total amount of the block copolymer is in this range. In this case, while the developer passes through the developer regulating member, the rolling of the developer is improved and the surface of the developer is triboelectrically charged, so that the insufficient charge of the developer is suppressed.

A typical configuration of a developer regulating member includes a regulating portion and a supporting member. The materials constituting the regulating portion and the support member may be the same material or different materials from each other. As the support member, a member capable of supporting the regulating portion can be appropriately used. Hereinafter, a form in which the regulating portion and the supporting member exist as separate and independent members will be described as an example, but the present invention is not limited to this, and both may be integrated.

Specific examples of the developer regulating member will be described with reference to FIGS. 2 to 4. In addition, in FIGS. 2 to 4, only a part of the developer carrier 1 is shown. The developer-supported body 1 is a developer-supported roller, and these figures show a cross section in a direction orthogonal to the rotation axis of the developer-supported roller. Further, with respect to the developer-supporting body 1 and the developer-regulating member 2, the "longitudinal direction" means a direction parallel to the rotation axis of the developer-supporting roller (direction perpendicular to the paper surface in FIGS. 2 to 4).

The developer regulating member 2 is composed of a regulating section 3 and a supporting member 4. The support member 4 is a plate-shaped member extending in the longitudinal direction of the developer-supporting roller. The support member 4 makes the contact between the regulating portion 3 and the developer more stable, and the developer can be triboelectrically charged more uniformly, so that it becomes easier to suppress the charge shortage of the developer. The developer regulating member 2 is fixed to the holder 44 and abuts on the surface of the developer carrier 1 with the fixing point 40 as a fulcrum. The holder 44 is fixed to the developer container 6 described later. With such a configuration, the developer regulating member 2 can easily form an intake port for introducing an appropriate amount of the developer between the developer regulating member 2 and the developer carrier 1, and is uniform and sufficient on the developer carrier 1. It is easy to form a developer layer having a large amount of charge. The abutting portion 43 is a portion of the regulating portion 3 that abuts on the surface of the developer carrier 1.

The restricting portion 3 can be arranged at one end of the support member 4 (FIGS. 2 and 3), and can be arranged in the vicinity of one end of the support member 4 (FIG. 4). Specifically, as shown in FIGS. 2 and 3, the restricting portion 3 can be arranged so as to cover one end surface of the support member 4 in the lateral direction (the end surface in the X direction in FIGS. 2 and 3). At this time, not only the end surface of the support member 4, but also a part of the contact support surface and a part of the surface on the opposite side thereof are covered with the regulation portion 3. Here, the "contact support surface" is a surface of the support member that comes into contact with the developer (the developer supported on the surface of the developer carrier) via the restricting portion.

Alternatively, as shown in FIG. 4, the restricting portion 3 may be formed only on the contact support surface. In FIG. 4, the regulating portion 3 is arranged at a predetermined distance from the one end surface of the support member 4. However, even when the regulating portion is formed only on the contact support surface, the regulating portion 3 may reach the one end surface.

Further, the shape of the contact portion of the regulating portion is not particularly limited, and may be a flat surface, a curved surface, a convex shape, a concave shape, or the like.

As shown in FIGS. 3 and 4, the developer regulating member 2 can have a protruding portion 41. The restricting portion 3 comes into contact with the developer (the developer supported on the surface of the developer carrier) at the contact portion 43. The protruding portion 41 is a portion of the developer carrier 1 extending from the contact portion 43 toward the supply side of the developer (X direction in FIGS. 3 and 4) to the contact portion 43. Then, there is a step in the thickness direction of the support member (Z direction in FIGS. 3 and 4) from the contact portion 43 to the projecting portion 41. The protruding portion is not in contact with the developer. The support member 4 can extend to the position of the protruding portion 41. The presence of the protruding portion 41 facilitates the incorporation of the developer between the developer carrier 1 and the developer regulating member 2, and further, the developer is frictionally charged in this incorporation space in a compact state. The surface of the projecting portion may be pushed up by the developer tightly packed in the gap between the surface of the developer carrier 1 and the projecting portion 41. However, since the edge portion that regulates the thickness of the developer layer can be secured by having the step, the thickness of the developer layer can be regulated more reliably.

In the examples shown in FIGS. 3 and 4, the developer regulating member 2 includes a convex portion forming the contact portion 43. The convex portion is formed by a part (see FIG. 3) or all (see FIG. 4) of the regulation portion 3.

[Regulatory Department]
The regulating portion used for the developer regulating member is made of a main material of a resin material including a thermoplastic acrylic resin, and is formed on the supporting member.

On the contact support surface of the support member 4, the thickness of the regulating portion 3 is preferably 1 μm or more and 1000 μm or less. When the thickness is 1 μm or more, it is easy to improve the durability against abrasion due to friction with the developer carrier, and when the thickness is 1000 μm or less, stable contact pressure with the developer carrier is obtained. Easy to get. The thickness of the regulation portion 3 here means the distance from the contact support surface of the support member 4 to the contact portion 43.

The regulation portion can be formed by extrusion molding, coating molding, sheet laminating molding, injection molding, or the like. Specifically, in the case of extrusion molding, a support member coated with an adhesive is installed in a molding die, and a heat-melted regulatory part raw material is injected into the molding die to be extruded together with the support member. Further, in the case of coating molding, the regulation portion raw material dispersed in the solvent is applied to the support member by a coating device such as a spray, and the solvent is dried to form the regulation portion on the support member. Further, in the case of laminating and molding a sheet, the raw material of the regulation part molded into a sheet by extrusion molding or the like is bonded to a support member coated with an adhesive and molded. In the case of injection molding, the raw material of the regulation part is injected into the mold cavity, cooled and molded.

In forming the regulating portion, an adhesive layer can be formed on the support member as needed. Examples of the material of the adhesive layer include polyurethane-based, polyester-based, ethylene-vinyl alcohol-based (EVA-based), and polyamide-based adhesives as hot-melt adhesives.

[Support member]
The material of the support member is not particularly limited, and examples thereof include surface-treated steel plates such as chromate-treated and lubricating resins, metals such as stainless steel, phosphor bronze and aluminum, and resins such as acrylic resin, polyethylene resin and polyester resin. can. When conductivity is required when using a resin, it is preferable to add a conductive material to the resin.

The thickness of the plate-shaped support member (distance in the Z direction in FIGS. 2 to 4) is preferably 0.05 mm or more and 3 mm or less. In particular, when the support member is a thin plate having a thickness of 0.05 mm or more and 0.15 mm or less, the support member has an appropriate spring property. Therefore, it is easy to bring the regulated portion into contact with the developer carrier with an appropriate contact pressure, and it is easy to regulate the developer on the developer carrier to an appropriate layer thickness. When the thickness of the support member is 0.8 mm or more, it is easy to attach the developer regulating member to the developing device, process cartridge, and electrophotographic image forming device and set its position, and install it without distortion. Is easy. Therefore, it becomes easy to stably contact the regulated portion with the developer carrier with an appropriate contact pressure.

When the material of the support member is metal, the support member can be formed by bending processing such as pressing, electrochemical machining, discharge machining, laser beam machining, or the like.

When the material of the support member is a thermoplastic resin, the support member can be molded by, for example, extrusion molding or injection molding. Specifically, in the case of extrusion molding, the support member can be molded by injecting a thermoplastic resin that has been heated and melted into a molding die. Further, in the case of injection molding, the thermoplastic resin can be injected into the mold cavity and cooled to form the support member.

When incorporating the obtained developer regulating member into the electrophotographic image forming apparatus, it may be attached to the holder 44 shown in FIGS. 2, 3 and 4. The restricting portion 3 of the developer regulating member 2 may be directly bonded to the holder 44, or the support member 4 may be bonded as shown in FIGS. 2, 3 and 4. Adhesion can be performed by an appropriate method such as the use of an adhesive or welding. For example, when the support member 4 is welded to the holder, it can be welded by irradiating the support member 4 in a spot or line shape using a YAG laser, a fiber laser, or the like.

[Conducting agent]
A conductive agent can be applied to the regulating portion, the support member, and the adhesive layer as needed. Examples of the conductive agent include an ionic conductive agent and an electronic conductive agent such as carbon black.

Specific examples of carbon black include "Ketchen Black" (trade name, manufactured by Lion Specialty Chemicals Co., Ltd.), conductive carbon black such as acetylene black, SAF, ISAF, HAF, FEF, GPF, and SRF. , FT, MT and other carbon blacks for rubber can be mentioned. In addition, carbon black for color ink and thermally decomposed carbon black that have been subjected to oxidation treatment can be used. The amount of carbon black used is preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic acrylic resin. The content of carbon black in the resin can be measured using a thermogravimetric analyzer (TGA).

In addition to the above carbon black, the following can be mentioned as usable electron conductive agents. Graphites such as natural graphite and artificial graphite; metal powders such as copper, nickel, iron and aluminum; metal oxide powders such as titanium oxide, zinc oxide and tin oxide; conductive polymer compounds such as polyaniline, polypyrrole and polyacetylene. These can be used alone or in combination of two or more, if necessary.

Examples of the ion conductive agent include the following. Perchlorates, including ammonium ions such as tetraethylammonium, tetrabutylammonium, lauryltrimethylammonium, dodecyltrimethylammonium, stearyltrimethylammonium, octadecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, modified aliphatic dimethylethylammonium, Chlorate, hydrochloride, bromine, iodate, borohydrochloride, trifluoromethylsulfate, sulfonate or bis (trifluoromethylsulfonic acid) imide salt; of lithium, sodium, calcium, magnesium Perchlorates, chlorates, hydrochlorides, bromines, iodates, borohydrochlorides, trifluoromethylsulfates, sulfonates or bis (tri), including such alkali metals or alkaline earth metals. Fluoromethylammonium) imide salt. Of these, alkali metal or ammonium ion trifluoromethyl sulfates and bis (trifluoromethylsulfonic acid) imide salts are preferable. Since these salts have a structure in which fluorine is contained in the anion, they are suitable because they have a large effect of imparting conductivity. These can be used alone or in combination of two or more, if necessary.

In addition, the restricting portion, the support member, and the adhesive layer may contain a charge control agent, a lubricant, a filler, an antioxidant, and an antiaging agent as long as the functions of the resin and the conductive agent are not impaired. ..

[Developer]
An example of the developing apparatus is shown in FIG. The developer 9 regulates the thickness of the developer container 6 for accommodating the developer 34, the developer carrier 1 for transporting the developer 34, and the developer layer on the surface of the developer carrier 1. It has a member 2. If necessary, a developer supply roller 7 or the like may be provided.

In such a developing apparatus 9, the developer supply roller 7 rotates in the direction of arrow c, and the developer 34 is pressure-bonded onto the developer carrier 1 that rotates in the direction of arrow b. The developer 34 pressure-bonded onto the developer carrier enters between the developer regulating member 2 and the developer carrier 1 as the developer carrier 1 rotates in the direction of arrow b, and when passing therethrough. , The surface of the developer carrier 1 and the restricting portion 3 of the developer regulating member 2 are rubbed against each other, and frictional charging and charge injection are performed. The charged developer 34 forms a thin layer on the surface of the developer carrier 1 and is conveyed out of the developer container 6 as the developer carrier 1 rotates. The developer on the surface of the developer carrier 1 moves and adheres to the electrostatic latent image of the photoconductor (electrostatic latent image carrier) 5 rotating in the direction of arrow a, and the electrostatic latent image is transferred to the developer image. Develop as (toner image) and visualize. The developer that is not consumed in the development of the electrostatic latent image and remains on the developer carrier 1 is collected in the developer container 6 from the lower part of the developer carrier 1 as the developer carrier 1 rotates, and the developer is supplied. It is peeled off from the top of the developer carrier 1 at the nip portion with the roller 7. At the same time, the rotation of the developer supply roller 7 supplies the new developer 34 in the developer container onto the developer carrier 1. On the other hand, most of the developer 34 stripped from the developer carrier 1 is conveyed and mixed in the developer in the developer container 6 as the developer supply roller 7 rotates, and the charged charge thereof is dispersed. Will be done.

[Process cartridge]
The process cartridge has the developing device and is configured to be detachably attached to and detachable from the main body of the electrophotographic image forming device. An example of the process cartridge is shown in FIG. The process cartridge shown in FIG. 6 has a developing device 9, a photoconductor 5, a cleaning device 12, and a charging device 11, which are integrated and detachably provided on the main body of the electrophotographic image forming device. As the developing apparatus 9, the same as the image forming unit of the electrophotographic image forming apparatus described below can be used. In addition to the above configuration, the process cartridge may also have a configuration in which a transfer member or the like for transferring the developer image on the photoconductor to the recording material is integrally provided together with the above member.

[Electrophotograph image forming apparatus]
The electrophotographic image forming apparatus has the developing apparatus. An example of the electrophotographic image forming apparatus is shown in FIG. In FIG. 7, image forming units a to d are provided for each color developer of yellow toner (developer), magenta toner (developer), cyan toner (developer), and black toner (developer). Each of the image forming units a to d is provided with a photoconductor 5 as an electrostatic latent image carrier that rotates in the direction of the arrow. Around each photoconductor 5, a charging device 11 for uniformly charging the photoconductor 5 and an exposure means (not shown) for irradiating the charged photoconductor 5 with a laser beam 10 to form an electrostatic latent image. A developing device 9 is provided which supplies a developing agent to the photoconductor 5 on which the electrostatic latent image is formed to develop the electrostatic latent image.

On the other hand, a transfer transfer belt 20 for conveying a recording material 22 such as paper supplied by the paper feed roller 23 is suspended on a drive roller 16, a driven roller 21, and a tension roller 19. The electric charge of the adsorption bias power supply 25 is applied to the transfer transfer belt 20 via the adsorption roller 24, and the recording material 22 is electrostatically adhered to the surface thereof for transfer. The transfer transfer belt 20 is movable in synchronization with the image forming units a to d.

A transfer bias power supply 18 for applying a charge for transferring the developer image on the photoconductors 5 of the image forming units a to d to the recording material 22 is provided. The transfer bias is applied via a transfer roller 17 arranged on the back surface of the transfer transfer belt 20. The developer images of each color formed in the image forming units a to d are sequentially superimposed and transferred onto the recording material 22 conveyed by the transfer transfer belt 20.

Further, the color electrophotographic image forming apparatus includes a fixing device 15 for fixing the developer image superimposed and transferred on the recording material 22 by heating or the like, and a transport device for discharging the image-formed recording material 22 to the outside of the apparatus (not shown). ) Is provided.

On the other hand, each image forming unit is provided with a cleaning device 12 having a cleaning blade for removing the transfer residual developer remaining on each photoconductor 5 without being transferred and cleaning the surface. The cleaned photoconductor 5 is in a state where an image can be formed and stands by.

The developing apparatus 9 provided in each of the image forming units is provided with a developing agent container 6 containing a developing agent. Further, the developer 9 is installed so as to close the opening of the developer container, and the developer carrier 1 is provided so as to face the photoconductor 5 at a portion exposed from the developer container.

In the developer container, at the same time as supplying the developer 34 to the developer carrier 1, a developer supply roller 7 for scraping off the developer remaining on the developer carrier 1 after development is provided. It is provided. Further, in the developer container, a developer regulating member 2 is provided which forms the developer on the developer carrier 1 in a thin film form and is triboelectrically charged. These are respectively arranged in contact with the developer carrier 1. The developer carrier 1 and the developer supply roller 7 rotate in the forward direction.

A predetermined voltage is applied to the developer carrier 1 from the developer carrier bias power supply 14. Further, a predetermined voltage is applied to the developer regulating member 2 from the developer regulating member bias power supply 13.

[E-Spart method]
As a method for measuring the variation in the developer charge, there is a charge amount distribution measurement method by a laser Doppler charge measurement method (E-Spart method using an E-Spart analyzer (trade name, manufactured by Hosokawa Micron)). In the E-Spart method, since the amount of charge of the developer in a charged state is measured in the air flow, useful information for grasping the developed state can be obtained. In particular, it is effective as a method for evaluating fog caused by insufficient charge of the developer. According to the studies by the present inventors, a good correlation is obtained between the ratio (%) of the number of low trivo developers having a peak charge amount of 30% or less and the fog caused by the insufficient charge of the developer. ..

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

[Example 1]
1. 1. Preparation of Thermoplastic Acrylic Resin Coating Liquid To toluene, the following resin X, resin Y, and conductive carbon black were added.
Resin X: Methyl methacrylate polymer (Mw = 25200), 50 parts by mass.
Resin Y: Normal butyl acrylate polymer (Mw = 55100), 50 parts by mass.
Conductive carbon black: manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denka Black (indicated as "CB" in Table 2), 20 parts by mass.

This mixture was dispersed in a sand mill (using glass beads having a diameter of 1 mm as media particles) for 2 hours, the glass beads were separated using a sieve, and then ethyl acetate was added so that the solid content concentration became 33% by mass. , A thermoplastic acrylic resin coating liquid was prepared.

2. 2. Manufacture of developer regulating member A regulatory portion was formed on the surface of the support member using the coating liquid obtained above. The support member is a phosphor bronze plate with spring elasticity (plate thickness 0.12 mm, width (length in the lateral direction) 22 mm, length on the side to which the resin coating liquid is applied (length in the longitudinal direction) 210 mm). ) Was used. By fixing this support member vertically in the longitudinal direction and applying the thermoplastic acrylic resin coating liquid obtained above while lowering the spray gun at a constant speed, the surface (both sides) of the support member is coated. A coating film having a uniform film thickness was formed. Further, this was dried and cured in a drying oven at 160 ° C. for 30 minutes to form a regulating portion, and a developer regulating member having the structure shown in FIG. 2 was obtained. The thickness of the regulating portion 3 was 10 μm. Further, the regulating portion 3 is provided in a range of 3 mm from one end thereof in the width direction of the support member.

3. 3. <Measurement 1: Endothermic peak temperature measurement of thermoplastic acrylic resin>
DSC measurement was performed using a differential scanning calorimeter (trade name: DSC Q2000, manufactured by TA Instruments) in accordance with Japanese Industrial Standards (JIS) K6240: 2011. At this time, 5.0 mg of the sample obtained by peeling from the regulation portion was weighed in an aluminum pan, and the temperature was raised from −100 ° C. to 150 ° C. at a heating rate of 20.0 ° C./min. The endothermic peak was calculated from the differential curve obtained by differentiating the DSC curve obtained by the DSC measurement. There were two endothermic peaks on the derivative curve. Of these, the peak with a high endothermic peak temperature (peak top temperature) was designated as peak A, and the peak with a low endothermic peak temperature was designated as peak B.

As a result of measuring the produced developer regulating member, the temperature of peak A was + 115 ° C and the temperature of peak B was −56 ° C. The measurement results are shown in Table 2.

4. <Measurement 2: Molecular weight measurement of thermoplastic acrylic resin>
The weight average molecular weight Mw was measured using a high-speed GPC device (trade name: HLC-8320GPC, manufactured by Tosoh Corporation). At this time, the concentration of the sample obtained by exfoliating from the regulation portion with a tetrahydrofuran (THF) eluent was adjusted to 0.5% by mass, and the sample was used as a measurement target. Using two columns (trade name: TSKgel SuperHM-M, manufactured by Tosoh Corporation), the measurement was performed at a flow velocity of 0.6 mL / min, and the weight average molecular weight Mw was calculated. The detector was RI (differential refractometer) and the standard material was polystyrene.

As a result of measuring the produced developer regulating member, the Mw of the peak A component was 25200 and the Mw of the peak B component was 55100. The measurement results are shown in Table 2. Of the resins forming the regulation portion, the component showing peak A is referred to as "peak A component", and the component showing peak B is referred to as "peak B component". The peak A component corresponds to the resin X, and the peak B component corresponds to the resin Y. In Table 2, the Mw of the peak A component is shown in the column of "Mw of the resin X", and the Mw of the peak B component is shown in the column of "Mw of the resin Y".

5. <Measurement 3: Measurement of component content of thermoplastic acrylic resin>
Using a nuclear magnetic resonance apparatus (trade name: ECX5002, manufactured by JEOL RESONANCE), the chemical structures of the peak A component and the peak B component were specified, and the mass ratio of the monomers constituting these components was measured. At this time, the measurement frequencies were 490 MHz ( ¹ H) and 123 MHz ( ¹³ C), the solvent was deuterated chloroform, and the reference material was tetramethylsilane ( ¹ H: 0 ppm ¹³ C: 0 ppm). The measurement modes were ¹ H-NMR, H-H COSY, ¹³ C-NMR, DEPT, HSQC, and HMBC. In addition, the component content (mass%) was calculated from the monomer mass ratio.

As a result of measuring the produced developer-regulating member, the peak A component was a methyl methacrylate polymer and the content was 50% by mass, and the peak B component was a normal butyl acrylate polymer and the content was 50% by mass. These contents are shown in Table 2.

6. Evaluation by electrophotographic image forming device The produced developer regulating member was incorporated into the electrophotographic image forming device, and performance evaluation and image output evaluation were performed. A laser beam printer (trade name: CLJ CP4525, manufactured by Hewlett-Packard Co., Ltd.) having the configuration shown in FIG. 7 was used as the electrophotographic image forming apparatus. First, the developed agent regulating member produced was loaded into the magenta cartridge of the electrophotographic image forming apparatus, and then left to stand in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 55% for 24 hours.

After outputting 5 solid white images at a speed of 10 sheets / minute, the operation of the printer was stopped in the middle of outputting one solid white image, and the following evaluation was performed.

・ <Evaluation 1: Amount of charge of developer>
The developer is sucked from the developer layer formed on the developer carrier using a suction nozzle having an opening with a diameter of 5 mm, and the amount of charge of the sucked developer and the mass of the developer are measured to measure the developer. The amount of charge (μC / g) was determined. The amount of charge was measured using a digital electrometer (trade name: 8252, manufactured by ADC).

As a result of measuring the produced developer regulating member, the developer charge amount was 50 μC / g. The evaluation results are shown in Table 3.

・ <Evaluation 2: Distributor charge distribution>
In the measurement of the developer charge distribution, the espart analyzer (trade name) of Hosokawa Micron Co., Ltd. is used to blow off the developer layer formed on the developer carrier with nitrogen gas, and the measuring unit (measurement cell) of the measuring device is used. ) Was introduced from the sampling hole. Further, the measurement was carried out until 3000 developers were counted. The ratio (%) of the number of low trivo developrs in the total developer measured using an ease part analyzer was determined. The definition of "low trivo developer" is a developer having a charge amount of 30% or less of the peak charge amount (maximum value of the measured developer charge amount).

As a result of evaluating the prepared developer regulating member, the ratio of the low trivo developer was 0.6%. The evaluation results are shown in Table 3.

・ <Evaluation 3: Cover>
Peel off the toner adhering to the photoconductor with a transparent tape (trade name: Polyester Tape No. 550, manufactured by Nichiban Co., Ltd.) and attach it to white paper (trade name: Business Multipurpose 4200, manufactured by XEROX). , An evaluation sample was obtained. Next, the reflection density (R1) of the evaluation sample was measured with a reflection densitometer (trade name: TC-6DS / A, manufactured by Tokyo Denshoku Co., Ltd.). At that time, a green filter was used as the filter. On the other hand, the reflection density (R0) was measured in the same manner for the reference sample in which only the transparent tape was attached to white paper. The amount of decrease in reflectance of the evaluation sample "R0-R1" (%) with respect to the reference sample was defined as the fog value (%).

As a result of evaluating the produced developer regulating member, the fog was 0.7%. The evaluation results are shown in Table 3.

[Examples 2 to 8, 11 to 13, 17 to 22, Comparative Examples 1 to 7]
A developer regulating member was prepared and carried out in the same manner as in Example 1 except that at least one of the material of the resin X, the material of the resin Y, and the number of added copies of the resin X and the resin Y was changed as shown in Table 1. It was subjected to the measurement 1 to the measurement 3 and the evaluation 1 to the evaluation 3 described in Example 1.

[Example 9]
To 100 parts by mass of the resin Z shown below, 20 parts by mass of conductive carbon black (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denka Black) was added.
Resin Z: A block copolymer of a thermoplastic acrylic resin (Mw = 56500, manufactured by Kuraray Co., Ltd., trade name: Clarity LA4285).

The obtained mixture is melt-kneaded at 200 ° C. using a twin-screw kneading extruder (manufactured by Toshiba Machine Co., Ltd., trade name: TEM-26SX), extruded into a cylinder with a diameter of 3 mm, cooled, and then 3 mm by a cutting machine. A resin material was prepared by cutting into pellets of corners. For the production of the support member, a long sheet of SUS304-CSP-1 / 2H material having a short side direction of 15.2 mm and a thickness of 0.08 mm was used.

An apparatus for manufacturing a developer regulating member, which is outlined in FIG. 8, was used. First, the produced pellet-shaped resin material was melted at 200 ° C. in the extrusion molding machine 101 and injected into the molding cavity of the extrusion die 102. At the same time, one end surface of the long sheet 105 in the lateral direction was run in the molding cavity of the extrusion die 102. As a result, the portion of the support member including the one end surface was covered with the molten resin material. The temperature of the mold 102 was set to 250 ° C.

This long sheet was discharged from the extrusion die 102, and the resin material was solidified by the cooler 103. A member was obtained in which the one end surface and two main surfaces (each portion from the one end surface to a predetermined distance) of the long sheet were covered with a solidified resin material. This member was cut to a length of 226 mm in the longitudinal direction by a cutting machine 104 to produce a developer regulating member 2 having the structure shown in FIG.

When the developer regulating member thus obtained was subjected to DSC measurement in the same manner as in Example 1, the temperature of peak A having a high endothermic peak temperature was + 115 ° C, and the temperature of peak B having a low endothermic peak temperature was −56 ° C. there were. Further, when the component content was measured by a nuclear magnetic resonance apparatus in the same manner as in Example 1, the peak A component was a methyl methacrylate polymer, the content was 51% by mass, and the peak B component was a normal butyl acrylate weight. Combined, the content was 49% by mass. Furthermore, when the regulated portion was observed using phosphotungstic acid as a staining agent with a transmission electron microscope (TEM), it was confirmed that the regulated portion had a microphase-separated structure as shown in FIG.

Further, the developer carrier according to this example was subjected to Measurement 1 to Measurement 3 and Evaluation 1 to Evaluation 3 described in Example 1.

[Example 10]
A developer regulating member was prepared in the same manner as in Example 9 except that a thermoplastic acrylic resin block copolymer (Mw = 60500, manufactured by Claret Co., Ltd., trade name: Clarity LA2270) was used as the resin Z, and Examples were made. It was subjected to the measurement 1 to the measurement 3 and the evaluation 1 to the evaluation 3 described in 1.

[Example 14]
A developer regulating member was prepared in the same manner as in Example 10 except that the conductive carbon black was not used, and was subjected to Measurements 1 to 3 and Evaluations 1 to 3 described in Example 1.

[Example 15]
Same as Example 10 except that 5 parts by mass of lithium trifluoromethanesulfonate (manufactured by Mitsubishi Materials Electronics Co., Ltd., trade name: Ftop EF-15; shown as “TfLi” in Table 2) was added as an ionic conductive agent. Then, a developer regulating member was prepared and subjected to Measurements 1 to 3 and Evaluations 1 to 3 described in Example 1.

[Example 16]
A developer regulating member was prepared in the same manner as in Example 14 except that 5 parts by mass of lithium trifluoromethanesulfonate (manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd., trade name: Ftop EF-15) was added as an ionic conductive agent. , And the measurement 1 to the measurement 3 and the evaluation 1 to the evaluation 3 described in Example 1.

The test conditions and results of Examples and Comparative Examples are shown in Tables 2 and 3. In the examples other than Comparative Examples 4 to 7, two endothermic peaks were present in the differential curve of the DSC curve. In Comparative Examples 4 to 7, only one endothermic peak was present in the differential curve of the DSC curve.

The developer regulating member of the embodiment is a developer regulating member using a thermoplastic acrylic resin having an endothermic peak having a peak top at each of + 50 ° C. or higher and + 20 ° C. or lower in the DSC differential curve. In the examples, it was found that a sufficient charge could be given to the developer and that the insufficient charge of the developer was suppressed. As a result, good results were obtained in the fog evaluation.

On the other hand, in Comparative Examples 1 to 7, since there is no endothermic peak having a peak top at + 50 ° C. or higher and + 20 ° C. or lower, the slipperiness and adhesiveness of the developer on the developer carrier do not fall within an appropriate range. .. As a result, the developer simply slides and moves on the developer regulating member, or the developer adheres to the developer regulating member and rolls the developer on the developer regulating member. I can't. Therefore, the proportion of the low trivo developer was high, and the fog was 10% or more.

201 A component showing an endothermic peak above + 50 ° C (first component)
202 A component showing an endothermic peak below + 20 ° C (second component)
1 Developer carrier 2 Developer regulator 3 Regulator 4 Support member 6 Developer container 9 Developer 40 Fixed point 41 Projection 43 Abutment

Claims (16)

It is a developer regulating member that regulates the thickness of the layer of the developer supported on the surface of the developer carrier, and has a regulating portion in contact with the developing agent, and the regulating portion contains a thermoplastic acrylic resin.
The thermoplastic acrylic resin has a DSC curve obtained when the temperature is raised from −100 ° C. to 150 ° C. at a heating rate of 20.0 ° C./min using a differential scanning calorimetry (DSC). The developer regulating member is characterized in that a first endothermic peak having a peak top at + 50 ° C. or higher and a second endothermic peak having a peak top at + 20 ° C. or lower are present in the differential curve of. The developer regulating member according to claim 1, wherein the thermoplastic acrylic resin contains a first polymer showing the first endothermic peak and a second polymer showing the second endothermic peak. The developer regulating member according to claim 2, wherein the first polymer has a weight average molecular weight of 1 × 10 ⁴ or more and 5 × 10 ⁴ or less. The developer regulating member according to claim 2 or 3, wherein the weight average molecular weight of the second polymer is 1 × 10 ⁴ or more and 1 × ¹⁰⁵ or less. The developer regulating member according to any one of claims 2 to 4, wherein the content of the first polymer is 20% by mass or more and less than 80% by mass with respect to the total amount of the thermoplastic acrylic resin. Claim 2 to the first polymer having a repeating unit derived from methyl methacrylate and the second polymer having a repeating unit derived from n-butyl acrylate or 2-ethylhexyl acrylate. The developer regulating member according to any one of 5. The first aspect of claim 1, wherein the thermoplastic acrylic resin is a block copolymer of a first polymer block showing the first heat absorption peak and a second polymer block showing the second heat absorption peak. The developer regulating member described. The developer regulating member according to claim 7, wherein the block copolymer has a weight average molecular weight of 1 × 10 ⁴ or more and 9 × ¹⁰⁵ or less. The developer regulating member according to claim 7 or 8, wherein the content of the first polymer block is 20% by mass or more and less than 80% by mass with respect to the total amount of the block copolymer. 7. The first polymer block contains a repeating unit derived from methyl methacrylate, and the second polymer block contains a repeating unit derived from n-butyl acrylate or 2-ethylhexyl acrylate. The developer regulating member according to any one of 9 to 9. The developer regulating member according to any one of claims 1 to 10, wherein the regulating unit contains a conductive agent. The developer according to any one of claims 1 to 11, further comprising a support member for supporting the restricting portion, and the restricting portion is arranged at one end of the supporting member or in the vicinity thereof. Developer control member. The developer regulating member has a protruding portion extending from the contact portion of the restricting portion in contact with the developer to the supply side of the developer to the contact portion, and the support member extends from the contact portion to the protruding portion. There is a step in the thickness direction of
The developer regulating member according to claim 12, wherein the support member extends to the position of the protruding portion. A developing apparatus including a developer carrier and a developer regulating member arranged in contact with the surface of the developer carrier, wherein the developer regulating member comprises claims 1 to 13. A developing apparatus characterized by being the developer regulating member according to any one of the following items. A process cartridge that can be attached to and detached from the main body of the electrophotographic image forming apparatus.
13. A process cartridge characterized by being a developer regulating member. An electrophotographic image forming apparatus comprising a developer carrier and a developer regulating member arranged in contact with the surface of the developer carrier, wherein the developer regulating member is claimed 1. An electrophotographic image forming apparatus according to any one of 13 to 13, which is a developer regulating member.

Images